Remove Null forgiving operator

[alex1ozr]

Description

Remove all instances of the null-forgiving operator (!) from the codebase and address the underlying nullability concerns properly. The null-forgiving operator suppresses compiler warnings but doesn't provide runtime safety, potentially hiding null reference issues.

Approach:

• Identify all usages of the ! operator throughout the project
• Replace with proper null checks, guard clauses, or nullable reference type handling
• Refactor code to make nullability explicit and handled safely
• Use appropriate patterns: null-coalescing (??), null-conditional (?.), .Required() or explicit validation
• Find any possible way to restrict usage of the ! operator via Roslyn analyzers

Expected outcome:
A codebase with explicit null handling, improved runtime safety, and enforced nullability discipline through static analysis.